Thermochemical scarfing method



Nov. 1967 c. R. GINGERICH ETAL 3 THERMOCHEMI CAL S CARFING METHOD Filed March 10, 1966 INVENTORS CEC/L R. G/NGER/CH RUDOLF/1' F. H/NSCHLAGE/P ALLAN R WANDELT ATTORNEY United States Patent O 3,354002 THERMOCHEMICAL SCARFING METHOD Cecil R. Gingerich, Farmington, Mich. and Rudolph F.

Hinschlager, West Orange, and Allan R. Wandelt, Warren Township, N.J., assignors to Union Carbide Corporation, a corporation o1 New York Filed Mar. 10, 1966, Sex}. N0. 533,277 8 Claims. (Cl. 148-95) This invention relates to therrnochernical scarfing the surface of a metal body and particularly to improvements to the basic method of granulating, trapping and rernoving the molten slag produced during such process, by the utilization of a fluid stream, e.g. Water, which is discharged to skim across the surface at high velocity. The basic method is disclosed by I. P. Thompson et a1. in U.S. Patent 2465297.

As disclosed in the above-referenced patent, during the,

thermochernical scarfing process a stream of oxidizing gas is directed obliquely against a reaction zone of molten metal which has been previously formed upon the surface of the body. In so doing, a thermochemical reaction is produced, which continues along the surface of the body as relative movement is produced between such body and the stream of oxidizing gas. As a result of this thermochernical scarfing reaction, a molten slag is produced which must be removed from the surface of the body. This is acomplished according to the basic reference by directing a stream of fluid, e.g. water, at high velocity so as to skim across the surface of the body and thereby impinge against and completely deflect the slag oft the surface thereof. The fluid stream also breaks the slag into small particles, chills it and directs the particles ofi" the surface into a slag chute.

While the basic method has been successfully used for many years, it is not entirely effective in trapping the fine slag spray that is deflected from the main fluid stream as Well as from the reaction itself. In addition, a considerable quantity of this slag spray is deflected in directiohs away from the slag chute. This has resulted in a substantial build-up and accumu-lation of slag upon the scarfing machine, slag target, roll table and srnoke hood, which necessitates more frequent maintenance thereto.

The object of the invention is to provide an improved method of trapping and rernoving slag produced during a scarfing rea-ction, such that substantially all of the slag produced will be removed, with little if any being deflected against the surfaces of the scarfing machine, slag target, roll table and smoke hood, etc.

According to one embodiment of the present invention, at least one main fluid stream is discharged at high velocity and positioned so as to skim across the surface of the body in front of the reaction zone. The purpose of the main stream is to trap most of the slag and to wash it 0if the surface being scarfed, into a slag chute.

At least one additional fluid stream is then directed across the surface of the body in front of the reaction zone, frorn a osition further above the surface than the main stream. The efiect of this is that the molten slag and spatter which escapes from or is deflected =by the main fluid stream is trapped by'the additional stream or streams and deflected into the slag chute. Preferably, two or more additional streams are utilized. They are prefera-bly positioned so as to partially surround the main stream. The volume fiow rateof each additional stream may be substantially lass than that of the main strearn.

This embodiment is particularly Well suited for the scarfing of wide metal bodies, i.e. slabs, where a relatively massive main stream is needed to traverse the entire surface thereof with sufiicient force to trap and push the slag laterally 011 the surface into the slag chute. In this 3354002 Patented Nov. 21, 1967 ice case, the smaller auxiliary streams act mainly to trap the fine slag spray which is not trapped by the main stream.

According to another embodiment of the invention, which has been found be admirably eflective when scarfing smaller sections, such as billets and blooms, a generally channel-shaped stream of fluid is directed across the surface of the body in front of the reaction zone, With the opening in the channel substantially facing the reaction zone. A fluid stream of this general configuration will act as a pocket to trap the slag and carry it laterally 011 the surface of the metal body. The channel-shaped strearn may be formed from a single nozzle of appropriate shape or alternatively, it may be fiormed from a plurality of spaced individual streams arranged so as to form this pattern.

A particularly efiective channel-shaped fluid stream has been formed frorn a plurality of individual streams arranged in a crescent type pattern, With the opening in the crescent facing the reaction zone.

In the drawings:

FIGURE 1 is an end view facing the reaction zone, of a metal body heing scarfed, and illustrating the slag removal method of the invention;

FIGURE 2 is a side view of the body to be scarfed and facing the fluid nozzles shown in FIGURE 1 and FIGURE 3 is a side view similar to FIGURE 2 but illustrating another embodirnent of the invention.

Referring to FIGURES 1 and 2, the metal body W to be scarfed is supported upon and moved by roll table R toward a scarfing unit M. A molten puddle of metal is formed upon the surface of the body at reaction zone Z, by preheat flames from the scarfing unit M. Thereafter a sheet-like stream of oxidizing gas S, e.g. oxygen, is directed obliquely against the molten puddle to cause a thermochemical reaction. Relative movement is then produced between the metal body W and the oxidizing gas stream S so as to continue the reaction along the surface length of the body.

As the scarfing reaction pr-oceeds, molten slag is produced and projected forwardly and upwardly from the reaction zone Z. 7

A substantial portion cf the molten slag comes into contact with a high velocity main stream 10 of fluid, e.g. water. The fluid stream is discharged from a nozzle 12 which is positioned so that the fluid Will skim across the surface of the metal body at a point slightly downstream of the reaction zone. The fluid strearn is discharged into a slag chute 14 adjacent the opposite side of the metal body. A significant portion cf the molten slag is broken up and deflected by the main strearn 10 and carried into the slag chute 14.

T0 trap and remove slag which is deflected away fron1 the slag chute by the main stream 10, in addition to molten slag which does not come into contact with the main stream, we direct additional streams 16 of fluid across the metal body and into the slag chute 14. The additional strearns are positioned with their central axis above the central axis of the main stream 10, and preferably such additional strearns partially surroundthe main stream as illustrated in FIGURE 2. Preferably, at least one of the additional streams 16 is oflset from the main strearn 10 toward the reaction zone. In this manner, a significant portion of the slag which is deflected up- Wardly frorn the main stream 10 is trapped by the additional strea-rns 16 and conveyed into the slag chute. In addition, a portion of the molten slag which does not come into contact With the main stream 10 impinges upon the additional stream or streams 16 whereupon it is broken up and carried to the slag chute 14.

When scarfing wide slabs it becornes diflicult to maintain the coherency of a sin-gle main stream due to the impinging thereagainst of molten slag. In such case it is advisable to back up the rnain stream with a secnd strearn wliich is skimmed across the suriace of the body. When a second main stream is used, it is usually necessary to locate the additional shielding streams so as to partially surround Only the main stream nearest the reaetion zone, as shown in FIGURE 2.

As an example of the water flows required in a typical situation, the top surface of a 95 inch wide metal body was scarfed with a flow rate of 325,000 c.f.h. of oxygen at a scarfing speed of the order of: 120 fest per minute. A rnain stream of water having a diametcr of approximately 2 inches and a flow rate of 310 gallons per minute was skimmed across the surface of the body. Three additional streams of water, positioned as shown in FIGS. 1 and 2were used to trap and rernove the slag deflccted away from the slag chute by the main stream. Bach of the additional streems had a diameter of approxirnately 1% inches, and each was discharged at a flow rate of about 200 gallons per minute.

The prirnary purpose of the additional streams is t0 act as a fluid shield for the main stream. When scarfing ide slabs it is often necessary to maintain more than one main fluid stream skimming across the surface of the body. In such case it is usually only necessary to shield the main stream nearest the reaction zone with the additi0nal fluid streanis.

Referring now to FIGURE 3, another ernbodiment of the invention is illustrated which is particularly efiective in trapping slag during the scarfing of metal bodies having relatively narrow surface widths, i.e. billets and blooms. Acc0rding to this embodirnent a fluid pocket is f1rned by direct'ing the fluid, e.g. water, in a channel shaped stream ac'ross the surface of the metal body at a point adjacent the reaction zone. T he channel-shaped strearn is formed so that the opening in the channel substantially faces the reaction zone. This type of patterned water stream acts as a pocket to trap the slag and carry it oif into the slag chute.

It will be noted that FIGURE 3 illustrates a crescent shaped channel pattern, having its opening facing the reaction zone. It should be understood, however, that numerous other channel-shaped configurations r'nay also be used, according to this invention.

It should also be notedthat the channel shaped stream may be formed frorn a plurality of individual streams arranged in a channel-shaped pattern as illustrated for example in FIGURE 3, or alternatively it may be formed into a continuous strearn by an appropriately shaped nozzle, in either case the objeet being to for-rn a type of fluid pocket so as to trap the slag and carry it laterally ofl the metal body.

As an illustration of this embodirnent of the invention, the top surface of a 10 inch wide metal billet was scarfed with aflow rate of 000 c.f.h. of oxygen at a scarfing speed of the -order of 120 feet per minute. Twelve individual strearns of water having a diameter of about inch each and a total flow rate of about 250 gallons per minute were arranged in a crescent facing the reaction zone (see FIGURE 3). The ability of this method of slag removal was excellent, it being far superior to the methods heretof-ore used in the art.

What is clain'1ed is:

1. In a thermochernical scarfing process wherein a stre'am of oxidizing gas is directed against a reaction zone of molten metal on the surface of a metal body to produce a thermochemical reaetion thereon, and relative movement between such strearn and the body is produced for continuing such reaction along the length of such surface, the improvernent for granulating and trapping molten sla-g produced during such reaction which comprises:

(l) directing at least one main fluid stream transversely of said surface in front of said reaction zone, while maint-aining such fluid strearn in im1nediate adjacency to such surface, to trap and granulatc a substantial portion of such slag, and push it laterally ofii said surface, and

(2) directing at least one additional fluid strearn transversely of said surface in front of said reaction zone, said additional fluid stream being positioned with its central axis further above the surface ot' the body than the central axis of said rnain fluid stream, Whereby substantially all of the granulated slag deflected by said main stream in addition to substantially all ungranulated slag which does not corne into contaet with said rnain stream will be trapped by said additional fluid stream and pushed off laterally from the surface of the body.

2. In a therrnochemical scarfing process as claimed in claim 1 wherein at least one of said additional fluid streams is positicined with its central axis oifset frorn the eentral axis of said fluid strean1, towar-d the reaction zone.

3. In a therrnochemical scarfing process as clairned in claim 1 wherein each additional fluid stream is of smaller volume flow rate than said main fluid strearn.

4. In a thermochemical scarfing process as claimed in clairn 1 wherein said additional streams at least partially surround said rnain stream.

5. In a thermochemical scarfing process as claimed in clairn 1 wherein two main strearns =of water are directed transversely of said surface in front of said reaction zone while rnaintaining said streams in immediate adjacency to such surface, and at least three additional strearns cf water are directed across such surface frorn positions partially surrounding the rnain water strearn located nearest to the reaction zone.

6. In a thermochemical scarfing process wherein a stream of oxidizing gas is directed against a reaction zone of molten metal on the snrface of a metal body to produce a therrnochernical reaction thereon, and relative movernent between such stream and the body is produced for continuing such reaction along the length of such surface, the improvement for granulating and trapping molten slag produced during such reaction which comprises directing a generally channel-shaped stream of fluid transversely of said surface in front of said reaction zone, with the opening in the channel substantially facing said reaction zone, whereby said stream will act as a pocket to trap the slag and carry it laterally oft said surface.

7. In a thermochemical scarfing process as claimed in claim 6 wherein said channel-shaped strearn of fluid is forrned froxn a plurality of spaced individual strearns.

8. In a thermochemical scarfing -process as claimed in claim 6 wherein said channel-shaped stream is forrned by a plurality of individual strcams spaced apart frorn one another in a crescent formation, with the opening in the crescent facing the reaction zone.

References Cited UNITED STATES PATENTS 2465,297 3/1949 Thoznpson et a1. 1489.5 3,163559 12/1964 Thornpson et al 1489.5

DAVID L. RECK, Primary Examiner.

W. W. STALLARD, A.gsistan t Examiner.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent N0. 3354002 November 21, 1967 Cecil R. Gingeriah et a1.

It is hereby certified that error appeara in ehe above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column 4, line 23, for "said" read seid main Signed and sealed this 4th day of March 1969.

(SEAL) Attest:

EDWABD J. BRENNER Commissioner of Patents Edward M. Flctcher, Jr.

Attesting Officer 

1. IN A THERMOCHEMICAL SCARFING PROCESS WHEREIN A STREAM OF OXIDIZING GAS IS DIRECTED AGAINST A REACTION ZONE OF MOLTEN METAL ON THE SURFACE OF A METAL BODY TO PRODUCE A THERMOCHEMICAL REACTION THEREON, AND RELATIVE MOVEMENT BETWEEN SUCH STREAM AND THE BODY IS PRODUCED FOR CONTINUING SUCH REACTION ALONG THE LENGTH OF SUCH SURFACE, THE IMPROVEMENT FOR GRANULATING AND TRAPPING MOLTEN SLAG PRODUCED DURING SUCH REACTION WHICH COMPRISES: (1) DIRECTING AT LEAST ONE MAIN FLUID STREAM TRANSVERSELY OF SAID SURFACE IN FRONT OF SAID REACTION ZONE, WHILE MAINTAIN SUCH FLUID STREAM IN IMMEDIATE ADJACENCY TO SUCH SURFACE, TO TRAP AND GRANULATE A SUBSTANTIAL PORTION OF SUCH SLAG, AND PUSH IT LATERALLY OFF SAID SURACE, AND (2) DIRECTING AT LEAST ONE ADDITIONAL FLUID STREAM TRANSVERSELY OF SAID SURFACE IN FRONT OF SAID REACTION ZONE, SAID ADDITIONAL FLUID STREAM BEING POSITIONED WITH ITS CENTRAL AXIS FURTHER ABOVE THE SURFACE OF THE BODY THAN THE CENTRAL AXIS OF SAID MAIN FLUID STREAM, WHEREBY SUBSTANTIALLY ALL OF THE GRANULATED SLAG DEFLECTED BY SAID MAIN STREAM IN ADDITION TO SUBTANTIALLY ALL UNGRANULATED SLAG WHICH DOES NOT COMES INTO CONTACT WITH SAID MAIN STREAM WILL BE TRAPPED BY SAID ADDITIONAL FLUID STREAM AND PUSHED OFF LATERALLY FROM THE SURFACE OF THE BODY. 